Post on 24-Feb-2016
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Chapter 22: Plants
What is a Plant?• Plant mostly multicellular
organisms of eukaryotic cells with think cell walls and that mostly get energy through photosynthesis
• Autotrophs produce their own energy (chlorophyll a and b in chloroplasts)
• Heterotrophs plants gain energy from decomposing organic material
What do Plants need to survive?• Reactants of photosynthesis:
– Sunlight, CO2, Water
• Gas Exchange:– Take in CO2 but also release O2
(byproduct that can limit photosynthesis)
• Minerals/Nutrients:– Absorbed from the soil through the
roots• Space:
– Crowding limits sunlight which lowers photosynthesis rate
– Photosynthesis is a very inefficient reaction, so a high rate is needed to survive
The Plant Kingdom• 5 Groups based on
Adaptations:1) Green Algae simplest
plants; seedless2) Bryophytes complex plants
but lack main plant structures; seedless
3) Seedless Vascular Plants typical plants but seedless
4) Cone-Bearing typical plants that produce seeds
5) Flowering seed producing plants with flower adaptations
The Plant Life Cycle• All plant groups follow
alternation of generation life cycles
• Diploid (2N) Phase:– Sporophyte multicellular
phase that produces spores– Spores grow into
gametophytes• Haploid (N) Phase:
– Gametophyte multicellular phase that produces gametes (sperm and eggs)
– Gametes fuse (fertilization) to make sporophyte
Green Algae• Can be unicellular or
multicellular (volvox)• Haploid cells most of the time
and reproduce by mitosis• Haploid gametes can fuse to
make diploid zygote that can be dormant for long periods of time– Survive unfavorable
environment• Must live in water or on moist
land; nutrient rich soil
Bryophytes• Multicellular plants but lack
leaves, stems, and roots– Lack of vascular tubes
means moss can only be 1 meter high
• Most common type is moss• Rhizoids simple root-like
tubes that help absorb water and nutrients
• Most of its life is the gametophyte form and requires water to mix gametes– Must live on moist ground
Seedless Vascular Plants • Club Moss, Horsetails, and
Ferns• Vascular tissue hollow tubs
inside the plant that allow the movement of water and nutrients– Xylem moves water– Phloem nutrients
• Rhizomes underground root system
• Sporophyte releases spores which grow into heart-shaped gametophytes; sperm and eggs need water to mix
Cone-Bearing Plants• Seed plant embryo,
energy supply, and protective coating (seed coat)– Allows spreading of plants
away from water sources• Gymnosperms “naked
seed”; sporophyte release pollen grains (male-gametophyte) from Pollen Cones – travel by wind to fertilize
ovules (eggs) in Seed Cones (pollination)
Flowering Plants• Must abundant plant forms• Angiosperms “enclosed seed”; flower
contains ovaries and pollen (sperm)– After fertilization ovaries develop into
fruit (contain seeds); animals eat fruit and spread seeds in droppings
• Flowers allow pollination by animals; much more efficient than wind
• Categorize plants by:– Soft or hard stems (wood)– Annual or biennial life cycles– # of cotyledons (seed leaves); monocots
(one) or dicots (two)– Flower petals in multiples of 3, 4, or 5– Vascular buddle formations– Types of leaves
Type of Flowering Plants• 5 Classifications:1) Amborella oldest known
angiosperms; only 1 species still exists
2) Water Lily large, showy flowers3) Magnoliids wide range of
flowers in both size and complexity
4) Monocots 20% of flowering plant species; includes rice, corn, wheat, orchids, lilies, and irises
5) Eudicots 75% of flowering plant species; very diverse class